The present invention relates generally to mobile radio telephones and, more particularly, to a distributed mobile radio telephone for use in a vehicle.
At present, there are three generally accepted ways to provide cellular telephone service to the driver of a vehicle. First, a standard, handheld cellular telephone may be used by the driver. The power for the handheld cellular telephone can be provided by the handheld unit""s own battery pack or by an adapter which plugs into the vehicle""s cigarette lighter. Second, a standard handheld cellular telephone can be held by a cradle mounted within the interior of the vehicle. The cradle may include an external speaker and microphone to permit hands-free operation once a call is established. Third, the vehicle may be provided with a built-in cellular telephone which is permanently fixed to the vehicle.
Each of the aforementioned solutions makes undesired tradeoffs among various design goals that include ergonomics, aesthetics, functional versatility, phone performance, expandability, and ease of installation and maintenance. For example, the first solutionxe2x80x94using a standard handheld terminalxe2x80x94provides versatility and ease of installation and maintenance at the expense of ergonomics, aesthetics, and phone performance. In brief, using a handheld cellular telephone requires awkward exertion on the part of the driver to position the phone next to a window. Even if the phone can be, positioned near a window, the vehicle""s body often obscures the RF path between the phone""s antenna and the cellular base station thereby limiting the phone""s performance. Also, the only functions available to the driver are those provided by the handheld phone.
The second solutionxe2x80x94mounting a handheld cellular telephone in a cradlexe2x80x94is an improvement over the first solution. Nevertheless, this solution also has drawbacks, primarily concerning ergonomics, aesthetics, and phone performance. Since the cradle is normally mounted outside the driver""s normal line of sight, the driver must shift his or her field of vision in order to use the cellular telephone. Further, cradles are normally sold as after-market devices whose appearance is not necessarily harmonious with the vehicle""s interior decoration. Cradles often suffer from dangling power cables, microphones, and control buttons. As in the first solution, the driver is limited to the functions provided by the handheld phone. Also, unless an external booster is usedxe2x80x94which brings its own problems regarding expense, installation, and aestheticsxe2x80x94the phone""s performance is limited by its power amplifier, which is designed to meet the battery constraints of a handheld terminal.
The third solutionxe2x80x94a built in cellular phonexe2x80x94provides improved aesthetics since it is normally designed to be harmonious with the vehicle""s interior. The trade off is in ergonomics, versatility, ease of maintenance, and ease of modification. Even in built in phones, the phone""s controls are normally placed outside the driver""s field of vision. Thus, the driver is required to shift his or her field of vision in order to operate the phone. Moreover, the freedom of having a detachable handheld telephone is lost. The phone cannot be removed from the vehicle when the driver departs from the vehicle. Furthermore, new features and functions cannot be readily added to a built in phone, nor can a built in phone be readily returned to its manufacturer for maintenance or upgrade.
The present invention relates to a radiotelephone for use in a vehicle. The radiotelephone includes a base unit mounted within the vehicle having a wide area transceiver for communicating with a station outside the vehicle, a control unit disposed in the vehicle remotely from the base unit, and a local area network for establishing a communication link between the base unit and the control unit. The local area network is adapted to transmit control and data signals between the base unit and the control unit. The control unit includes a keypad for entering commands and data which are transmitted to the base unit via the local area network, and a display for displaying information to the user. The control unit may also include a speaker and microphone. Alternatively, the speaker and microphone may be contained in a remote audio unit which is linked to the base unit via the local area network. In a preferred embodiment of the invention, a first local area transceiver is located with the control unit, and a second local area transceiver is located with the base unit to provide wireless communication between the base unit and the control unit. If a remote audio unit is used, a third local area transceiver would be located in the remote audio unit.
The control unit is typically mounted on the steering wheel of the vehicle. The control unit may be fully integrated into the steering column of the vehicle or, alternatively, may be a self-contained unit which attaches to the steering wheel of the vehicle. Power for the control unit may be provided by the vehicle""s battery, by a solar panel disposed within the vehicle, or by its own batteries.
In one embodiment of the invention, the base unit is a closed box which is concealed within the vehicle. For example, the base unit may be mounted in a console or in a trunk of the vehicle. User interaction with the base unit is strictly through the control unit. In this embodiment, certain components of the base unit, such as the wide area transceiver, may be embodied in cards which plug into the base unit. This allows for easy upgrading and repair of the base unit.
The base unit could comprise a standard hand-held radiotelephone. In this embodiment, the local area transceiver could be incorporated into the radiotelephone, or may reside in removable battery pack which attaches to the radiotelephone. A third option is to place the transceiver in a separate adapter which connects to the radiotelephone. With regard to the third option, the adapter may consist of a cradle for receiving and holding the hand-held radiotelephone. One advantage of locating the transceiver within either a.removable battery pack or an adapter is that the transceiver becomes an accessory which can be offered as an option to the user.
In another embodiment of the invention, the distributed components of the radiotelephone may communicate over a LAN which is inherent to the vehicle. Oftentimes, the vehicle""s manufacturer will include a local area network in a vehicle which ties together various systems of the vehicle. The control unit, base unit, and audio units of the present invention may use the excess capacity of the vehicle""s own LAN to communicate with one another. Because the radiotelephone shares the LAN with various components of the vehicle, the radiotelephone may be used to augment or work with the inherent systems on the vehicle. For example, the vehicle""s security system could be programmed to place a telephone call notifying local law enforcement authorities if the vehicle is stolen. This notification may include the position of the vehicle if the vehicle also has an on-board GPS receiver.